SiC single crystals are thermally and chemically very stable, superior in mechanical strengths, and resistant to radiation, and also have superior physical properties, such as high breakdown voltage and high thermal conductivity compared to Si single crystals. They are therefore able to exhibit high output, high frequency, voltage resistance and environmental resistance that cannot be realized with existing semiconductor materials, such as Si single crystals and GaAs single crystals, and are considered ever more promising as next-generation semiconductor materials for a wide range of applications including power device materials that allow high power control and energy saving to be achieved, device materials for high-speed large volume information communication, high-temperature device materials for vehicles, radiation-resistant device materials and the like.
In the prior art, single crystal SiC devices are fabricated by growing a large-diameter long bulk crystal known as an ingot, on a seed crystal substrate by a sublimation process or the like, cutting out a plurality of SiC wafers to a prescribed thickness from the single ingot, and forming on the SiC wafers the single crystal SiC epitaxial films that are to be the active regions of semiconductor devices. Formation of each single crystal SiC epitaxial film is carried out mainly by using a chemical vapor deposition method (CVD), wherein a starting material is supplied from a gas phase to form a desired epitaxial film (PTL 1).